Chief judge Ian Boardman is now deciding which centre wins the overall national award, and it will be announced at the GCA annual conference on 25-27 January at the Marriott Forest of Arden Hotel.
Stratford Garden Centre planteria manager Lauren Green said: "Plants are at the very core of our business and this competition is about the whole plant experience from the moment customers arrive on the car park, throughout the garden centre.
"The competition is tightly contested and we're judged against our peers by industry experts. This is the first year that we've entered so to be named the Midlands winner is incredible."
WINNERS (under £3m category)
North West Lady Green Garden Centre, Merseyside; All In One Garden Centre, Greater Manchester
North East Cowell's Garden Centre, Tyne & Wear
Midlands Webbs of Wychbold, Worcestershire; Stratford Garden Centre, Warwickshire
North Thames The Van Hage Garden Company, Great Amwell, Hertfordshire; Sunshine Garden Centre, North London
South Thames Stewarts Garden Lands, Christchurch, Dorset; Stewarts Country Garden Centre, Wimborne, Dorset
Wales & West Trelawney Garden Centre, Cornwall; Raglan Garden Centre, Monmouthshire.